The invention relates to a high frequency mixer stage comprising a field-effect transistor tetrode having two gate electrodes, with the high frequency input signal being fed to one of the gate electrodes. A mixer stage of this type is known, for example, from DE-PS German Pat. No. 21 59 592. In the known circuit, a field-effect transistor tetrode is combined with an ordinary field-effect transistor. The high frequency input signal is fed to one gate electrode of the tetrode, while the oscillator frequency from a parallel resonant circuit is fed to the second gate electrode of the tetrode. Connected to the drain electrode of the tetrode is a further parallel resonant circuit with which the intermediate frequency component is filtered out and coupled out inductively.
The known circuit is relatively sophisticated, since in addition to the tetrode a further field-effect transistor is required and a special local oscillator must be provided.